Most of the prior art packers utilize packing elements made of elastomeric materials where the packers are to function in wells having nominal temperatures. Prior packers designed to function in wells with elevated temperatures are basically mechanically the same as the units utilizing elastomeric sealing members with the only exception being that the packing elements are constructed of a combination plastic and asbestos material. Generally these materials have a tightly braided asbestos fiber or a closely packed asbestos and plastic composition material and thus they are relatively hard to mechanically compress. Both of these general configurations of packing material are constructed so that when the packer is set, they will be enlarged around the exterior periphery of the packer to establish a seal within the well casing. The expanding and sealing capabilities of this configuration of sealing elements is limited because of the ability of the relatively tightly packed material to change shape and have its outer perimeter significantly enlarged. As a result of this, these types of packers do not function properly in uncased well bores.